Telephone-transmitter



(No Model.)

- H. B. LYTLEL TELEPHONE. TRANSMITTER.

No. 260,488. PatentedJulyAT 188 2,

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I UNITED STATES PATENT OFFICE HENRY B. LYTLE, OF BOSTON, MASSACHUSETTS.

' TELEPHONE-TRANSMITTER.

, SPECIFICATION forrriing part of Letters Patent No. 260,488, dated July4, 1882.

To all whom it may concern Be it known that I-, HENRY B. LYTLE, ofBoston, in the countyof Suffolk and State of Massachusetts, haveinvented certain Im provements in Telephone-Transmitters, of which thefollowing is a specification.

My improvement relates to that form of transmitting-telephone in whichthe undulations or variations in the strength of an electric currentnecessary for reproducing articulate sounds in a receiving-instrumentare produeed by varying the resistance of the circuit throughcorresponding variations of the pressure between two electrodes of thecircuit. A well-known form of such an instrument is the Blaketransmitter, 'to which I have especially applied my invention.Exp'erience has demonstrated that the extreme sensitiveness of thisinstrument, which in certain circumstances is advantageous, becomes apositive evil when the instrument is used as the transmitting-telephoneof an operator in the cen: tral station of a telephone-exchange, sinceit causes the extraneous sounds due to the business of the entireroomand the several voices of the different operators to be conveyedover any circuit which may be temporarily connected with the office tothe annoyance of the subscriber and to the prejudice of the service ofthe exchange. Moreover, it has been discovered that a Blake transmitter,when set up in mills and factories, acquires, in virtue-of the inces-'sant vibrations of the walls of such buildings, a constant andcorresponding vibration of its electrodes, and generates in consequencethereof, when being used, aloud humming noise, which, when reproduced inthe receiving-telephone, drowns and renders confused and indistinct thegenuine and legitimate spoken words of the orally-transmittedcommunications.

To remedy these practical difliculties, and to maintain the delicacy andsensitiveness of a transmitting-telephone while eliminating its tendencyto collect extraneous vibrations, is the object of my invention.

To this end it consists in the combination, as hereinafter described,with and between the adjusting-lever and the eleotrode-carryin gsprin g,

- of a block of some non-resonant substance,

which at all times tends to check any abnormal vibration of theelectrodes upon one another.

Application filed February], 1882. (No model.)

The accompanying drawing represents a ver- 'tical section of atransmitter containing my in- 1 vention.

B represents a box or casing in which the mechanism of a telephoneembracing my improvement is inclosed, and A. is the top or cover of saidbox,which is perforated to serve as a mouth-piece.

'D and E are springs which respectively carry the platinum electrode 19and the carbon electrode 0, which is fixed to the front of the weight w.The spring E is heavier than the spring 1), and from its greaterstrength tends to keep the platinum electrode 10 incontact with thediaphragm O. The springs D and E areboth suspended from the horizontalarm m of the metallic adjusting lever G and are insulated from oneanother by a piece of hard rubber or other non-conductor, r. The springD is connected by awire (not shown) to one of the batterywires, and thespring E is in contact with the arm at ot' the adjustinglever G, andthence through the metal casing B with the other battery-wire.

- Between the spring E, atits point of attachment, and the main stem ofthe adjusting-lever G I place a piece of cork or other non-resonantmaterial, a. is adjusted back by means of the screw 12, and when thescrew b is tightened up to give the requisiteinitial pressure the corkis also made to fittightlyin place, and will then remain securelywithout any other fastening. Yet, if preferred, 1 may secure it with theset-screw m passing through its center and entering the arm m of thelever. The size of the cork which I have found to be most suitable isabout threeeighths of an inch square and about one-tenth of an inchthick. By this arrangement the transmitter is prevented from absorbingextraneous vibrations and sounds in the room which are not intended fortransmission. It is also prevented from breaking when loudly spokeninto, and does not hum when set up on the walls of factories and otherplaces, which This fits easily when the lever G ordinarily tends togreatly jar the electrodes i and no alteration is required at anytime,while heretofore it has been found practically impossible tomaintain a constant adjustment. I have also found that the range ofadjustment in a transmitter constructed as hereinbefore described, ismaterially amplified.

I claim 1. The combination, in a telephone-transmitter, with theadjusting-lever and spring carrying the outer electrode, of a block,plate, or piece of non-resonant material-such as corkinterposed betweensaid lever and spring, substantially as described.

2. The combination, in a transmitting-telephone, with theadjusting-lever G and contact-springs E and D, depending therefrom, ofthe non-resonant and resilient dampener a,in-

1882. HENRY B. LYTLE.

Witnesses:

GEO. WILLIS PIERCE, THOS. D. LooKwooD.

